title: Effect of weight loss on liver free fatty acid uptake and hepatic insulin resistance.
abstract: OBJECTIVE
  Weight loss has been shown to decrease liver fat content and whole-body insulin resistance. The current study was conducted to investigate the simultaneous effects of rapid weight reduction with a very-low-calorie diet on liver glucose and fatty acid metabolism and liver adiposity.
  
  
  OBJECTIVE
  We hypothesized that liver insulin resistance and free fatty acid uptake would decrease after weight loss and that they are associated with reduction of liver fat content.
  
  
  METHODS
  Thirty-four healthy obese subjects (body mass index, 33.7 +/- 8.0 kg/m(2)) were studied before and after a very-low-calorie diet for 6 wk. Hepatic glucose uptake and endogenous glucose production were measured with [(18)F]fluorodeoxyglucose during hyperinsulinemic euglycemia and fasting hepatic fatty acid uptake with [(18)F]fluoro-6-thia-heptadecanoic acid and positron emission tomography. Liver volume and fat content were measured using magnetic resonance imaging and spectroscopy.
  
  
  RESULTS
  Subjects lost weight (11.2 +/- 2.9 kg; P < 0.0001). Liver volume decreased by 11% (P < 0.002), which was partly explained by decreased liver fat content (P < 0.0001). Liver free fatty acid uptake was 26% lower after weight loss (P < 0.003) and correlated with the decrement in liver fat content (r = 0.54; P < 0.03). Hepatic glucose uptake during insulin stimulation was unchanged, but the endogenous glucose production decreased by 40% (P < 0.04), and hepatic insulin resistance by 40% (P < 0.05).
  
  
  CONCLUSIONS
  The liver responds to a 6-wk period of calorie restriction with a parallel reduction in lipid uptake and storage, accompanied by enhancement of hepatic insulin sensitivity and clearance.
authors.affiliation: Turku PET Centre, Turku University Hospital, P.O. Box 52, FIN-20521, Turku, Finland.
authors.forename: Antti P M
authors.initials: AP
authors.lastname: Viljanen
authors.forename: Patricia
authors.initials: P
authors.lastname: Iozzo
authors.forename: Ronald
authors.initials: R
authors.lastname: Borra
authors.forename: Mikko
authors.initials: M
authors.lastname: Kankaanpää
authors.forename: Anna
authors.initials: A
authors.lastname: Karmi
authors.forename: Riikka
authors.initials: R
authors.lastname: Lautamäki
authors.forename: Mikko
authors.initials: M
authors.lastname: Järvisalo
authors.forename: Riitta
authors.initials: R
authors.lastname: Parkkola
authors.forename: Tapani
authors.initials: T
authors.lastname: Rönnemaa
authors.forename: Letizia
authors.initials: L
authors.lastname: Guiducci
authors.forename: Terho
authors.initials: T
authors.lastname: Lehtimäki
authors.forename: Olli T
authors.initials: OT
authors.lastname: Raitakari
authors.forename: Andrea
authors.initials: A
authors.lastname: Mari
authors.forename: Pirjo
authors.initials: P
authors.lastname: Nuutila
mesh_terms: D002149:Energy Intake; D005230:Fatty Acids, Nonesterified / Q000378:metabolism*; D005260:Female; D005947:Glucose / Q000378:metabolism; D006801:Humans; D007333:Insulin Resistance; D008099:Liver / Q000378:metabolism*; D008297:Male; D014280:Triglycerides / Q000032:analysis; D015431:Weight Loss / Q000502:physiology*
chemical_list: D005230:Fatty Acids, Nonesterified; D014280:Triglycerides; D005947:Glucose